The present invention relates generally to a thread tapping form which is used to form an internal thread convolution in a member. More specifically, the present invention relates to a thread tapping form having a leading section which parts the material of the member to initiate the formation of the flanks of an internal thread convolution and a side section which presses against the flanks of the internal thread convolution to further form the surfaces of the flanks.
A known thread tapping form is disclosed in U.S. Pat. No. 1,309,232. This known thread tapping form includes a thread forming tooth or projection which, when viewed along the axis of a tap, has a generally triangular configuration. It should be noted that the thread forming tooth disclosed in this patent does not have a long leading edge to enter the material positively, a flat crest to assist in forming the desired helix angle or a flat side surface area which extends between the root and crest of the thread. In addition, the thread forming tooth disclosed in this patent has a configuration such that it will cut away a portion of the member in which a hole is to be tapped.
Other thread tapping forms are disclosed in U.S. Pat. No. 3,426,642. These thread tapping forms are associated with a self-tapping screw. Some of the thread tapping forms disclosed in this patent are formed as bulges in the crest and flanks of a thread. In other embodiments, the thread tapping forms appear as bulges which are disposed on the shank of the fastener without a thread between the bulges.